The present disclosure relates to a development device configured to supply a developer to an image carrier and to an image forming apparatus including the same.
An electrophotographic image forming apparatus is configured to form an image through processes of forming an electrostatic latent image by irradiating a beam formed on the basis of image information to a circumferential surface of an image carrier (a photosensitive drum), of transferring a toner image formed by supplying a toner (a developer) to the electrostatic latent image from a development device on a sheet, and of carrying out a fixing process.
In recent years, with advances of high-speed processing and color printing in the image forming apparatus, an apparatus configuration is becoming sophisticated and an increase of rotational speed of a developing roller and a toner agitation member in the development device is required in order to correspond to the high-speed processing. Due to that, a pressure within the development device easily becomes positive, i.e., higher than an atmospheric pressure. If the pressure within the developing device becomes positive, when the toner is supplied from the developing device to the image carrier, there is a possibility that a part of the toner floats, leaks out of a toner supplying port of the developing device facing to the image carrier, and contaminates an inside of the image forming apparatus by becoming as scattering toner.
In order to solve the scattering toner, there is a developing device provided with an airflow passage formed with a cover member, such as a developing case, covering a part of an outer circumferential surface of a developing roller, a suction fan generating an airflow in the airflow passage, and a toner filter that collects toner within the airflow. This developing device sucks the air within the developing case by the suction fan, thereby suppressing the toner from floating even in a condition in which a developing process is quickened.
There is also a developing device provided with an air inlet part (an air inflow port) through a wall part of a developing case facing to an lower part of a developing roller and a dust collecting box that introduces air flown into the developing case from the air inlet part to remove floating toner within the air. This developing device is provided with a flow passage formed by a plurality of meandering baffle plates within the dust collecting box to inertially collect the toner by causing the floating toner within the introduced air collide against the baffle plates. The air from which the floating toner is removed is discharged out of an air outflow port.
However, the former developing device mentioned above has a problem that a dedicated fan is required for sucking the toner floating within the developing device to the outside of the developing case, so the device is enlarged.
The latter developing device mentioned above also has a possibility that the floating toner within the developing case leaks out through the air inlet part (an air inflow port).